Re: [PATCH v2 4/4] riscv: dts: spacemit: Add Milk-V Jupiter board (M1)

From: Aurelien Jarno <aurelien@aurel32.net>
To: Yixun Lan <dlan@kernel.org>
Cc: linux-kernel@vger.kernel.org, Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	"open list:RISC-V ARCHITECTURE" <linux-riscv@lists.infradead.org>,
	"open list:RISC-V SPACEMIT SoC Support"
	<spacemit@lists.linux.dev>
Subject: Re: [PATCH v2 4/4] riscv: dts: spacemit: Add Milk-V Jupiter board (M1)
Date: Thu, 30 Jul 2026 12:13:38 +0200	[thread overview]
Message-ID: <amsj0kK6LtnxRT_J@aurel32.net> (raw)
In-Reply-To: <20260730085424-GKK76518@kernel.org>

Hi Yixun,

On 2026-07-30 08:54, Yixun Lan wrote:
> Hi Aurelien, 
> 
> 
> On 18:00 Wed 29 Jul     , Aurelien Jarno wrote:
> > Add support for the Milk-V Jupiter board with the M1 CPU. The M1 differs
> > from the K1 only by its package, which provides improved cooling
> > performance and allows it to run at up to 1.8 GHz instead of 1.6 GHz.
> > 
> > Add m1-opp.dtsi to define the 1.8 GHz operating point and the
> > corresponding core voltage, based on the upstream kernel. Include it
> > from m1-milkv-jupiter.dts. Raise the maximum buck1 voltage to 1.116V to
> > match the new operating point.
> > 
> While checking the schematics, the buck1,2 provide power supply both
> for cpu core and AVDD09 domain - check schematics page 9/25 [1]
> 
> the R81 is NC, so buck1,2 is actually all power supply, raise voltage will
> result high risk to damage the chip (overvoltage of AVDD09 domain), so

Yes, both buck1 and buck2 supply the CPU core. I only raised buck1 here, 
because it's the only one controlled by the cpu scaling, but in practice 
I believe that configuring the PMIC as Dual-Phase Mode couple the two 
regulator at the hardware level and only the first one need to be set. 
See my analysis there:
https://lore.kernel.org/spacemit/178402025712.1568061.9223355686030414906.b4-ty@b4/T/#m828e80aaf454606baafbd43e3795089ba397145f

But I can indeed raise both values for consistency.

> a safe strategy would to test if M1 able to run at 1.8G without voltage 
> change (still at 1.05v)?

I'll try that, but my guess is that given the vendor kernel raises the 
voltage to 1.116V, it is actually needed.

Regards
Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                     http://aurel32.net

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